17-year-old Chou Tzuyu in a romantic relationship with fellow classmate Park Chaeyoung. Her best friend is Myoui Mina. Little does Tzuyu know that her best friend has a massive obsession with her and wants her to herself. When Myoui can't control her jealousy she strikes and kills the girl when Tzuyu finds out her own best friend is the reason for her lover's death things don't go too well between them.